Journal ArticleDOI
Influence of Barotropic Shear on the Poleward Advection of Upper-Tropospheric Air
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In this article, the characteristics of the poleward advection of upper-tropospheric air are investigated using meteorological analyses and idealized numerical models, and the role of ambient barotropic flow is further examined by considering the flow in two numerical models.Abstract:
The characteristics of the poleward advection of upper-tropospheric air are investigated using meteorological analyses and idealized numerical models. Isentropic deformations of the tropopause during Northern Hemisphere winter are examined using maps of Ertel's potential vorticity together with contour advection calculations. Large poleward excursions of upper-tropospheric air are observed during Rossby wave breaking events. These “poleward” breaking events occur in regions of diffluence (over the eastern Atlantic Ocean-Europe region, and over the eastern Pacific Ocean-North America region), and the evolution of the tropospheric air depends on the local, meridional shear: in anticyclonic (or weak cyclonic) shear the tropospheric air tilts downstream, broadens, and wraps up anticyclonically, whereas in cyclonic shear the tropospheric air tilts upstream, thins, and is advected cyclonically. The role of ambient barotropic flow is further examined by considering the flow in two numerical models: a pl...read more
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Journal ArticleDOI
Climatology of Intrusions into the Tropical Upper Troposphere
TL;DR: This paper found that Rossby wave breaking events occur almost exclusively within westerly ducts, with more events in the presence of stronger equatorial westerlies, and that there is strong interannual variability in the frequency of Pacific events with fewer events during the warm phases of ENSO (consistent with the changes in the basic flow).
Journal ArticleDOI
Identification and ERA-15 Climatology of Potential Vorticity Streamers and Cutoffs near the Extratropical Tropopause
Heini Wernli,Michael Sprenger +1 more
TL;DR: In this paper, a novel approach is introduced to identify potential vorticity streamers and cutoffs as indicators of Rossby wave breaking near the extratropical tropopause and to compile climatologies of these features on different isentropic surfaces.
Journal ArticleDOI
Bidimensional Diagnostics, Variability, and Trends of Northern Hemisphere Blocking
TL;DR: In this paper, the authors introduced a set of new bidimensional diagnostics based on geopotential height that provide information about the occurrence, the duration, the intensity, and the wave breaking associated with the blocking.
Journal ArticleDOI
Wave‐breaking characteristics of midlatitude blocking
TL;DR: In this article, Rossby wave breaking is identified as a key process in blocking occurrence, as it provides the mechanism for the meridional reversal pattern typical of blocking, and two indices are designed to detect the major properties of wave breaking, i.e. the orientation (cyclonic/anticyclonic-direction of breaking or DB index) and the relative contribution of air masses (warm/cold relative intensity or RI index).
Journal ArticleDOI
Blocking and Rossby Wave Breaking on the Dynamical Tropopause in the Southern Hemisphere
TL;DR: In this article, Rossby wave breaking on the dynamical tropopause in the Southern Hemisphere (the −2-PVU surface) was investigated using the ERA-40 dataset.
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